Antifungal Effect of Metabolites from a New Strain Lactiplantibacillus Plantarum LPP703 Isolated from Naturally Fermented Yak Yogurt

Abstract

The antifungal effect of metabolites produced by a new strain of <i>Lactiplantibacillus (Lpb.) plantarum</i> LPP703, isolated from naturally fermented yak yogurt, was investigated. The results showed that <i>Lpb. plantarum</i> LPP703 significantly inhibited four fungal species, including <i>Penicillium</i> sp., <i>Rhizopus delemar</i>, <i>Aspergillus flavus</i>, and <i>Aspergillus niger</i>. The metabolites produced after 20 h of <i>Lpb. plantarum</i> LPP703 fermentation showed the highest antifungal activity against <i>Penicillium</i> sp. Compared with the control group, the <i>Lpb. plantarum</i> LPP703 metabolites-treated <i>Penicillium</i> sp. spores were stained red by propidium iodide, indicating that the cell membrane of the fungal spores was damaged. Moreover, the antifungal effect of the <i>Lpb. plantarum</i> LPP703 metabolites on <i>Penicillium</i> sp. was not changed after heating or treatment with various proteases, but showed a sharp decrease when the pH value was regulated to 5.0 or above. The oleamide, trans-cinnamic acid, and citric acid were the three most abundant in the <i>Lpb. plantarum</i> LPP703 metabolites. Molecular docking predicated that the oleamide interacted with the active site of lanosterol 14-alpha-demethylase (CYP51, a crucial enzyme for fungal membrane integrity) through hydrogen bonds and had the lowest docking score, representing the strongest binding affinity to CYP51. Taken together, the metabolites from a new strain of <i>Lpb. plantarum</i>, LPP703, had potent antifungal activity against <i>Penicillium</i> sp., which might be associated with the damage of the active ingredient to fungal membrane integrity. This study indicated that <i>Lpb. plantarum</i> LPP703 and its metabolites might act as biological control agents to prevent fungal growth in the food industry.